Technical Field
The embodiments herein generally relate to the field of molecular nanotechnology. The embodiments herein particularly relate to nanomedicines based drug delivery systems and gene transfer systems. The embodiments herein more particularly relate to a method and system for synthesizing nanoparticles for drug delivery and gene transfer.
Description of the Related Art
In nanotechnology, a particle is defined as a small object that becomes a whole unit with respect to its transport and properties. The particles are further classified according to the diameter. The “nanoparticles” have a diameter within a range of 1 and 100 nanometer.
Nanotechnology has offered many advantages for novel drug delivery systems and gene delivery systems in terms of both time-controlled drug delivery, site-directed drug delivery and site-directed gene delivery. These advantages are mainly derived from the very small (submicron) sizes of the nanostructures used as nanocarriers for drugs or genes as well as the possibility of engineering the carrier structure and/or surface according to the particular biological requirements.
“Nanomedicine” is the medical application of nanotechnology. Nanomedicine ranges from the medical applications of nonmaterial's to nano-electronic biosensor and even possible future applications of molecular nanotechnology.
The current problems for nano-medicine involve understanding the issues related to toxicity and the environmental impact on a nanoscale material. The nano-medicine has provided the possibility of delivering drugs and genes to specific cells using nanoparticles. The overall drug consumption and side effects are lowered significantly by depositing an active agent only in a morbid region at a required and appropriate dosage thereby eliminating a need for a higher dosage.
The drug delivery and gene delivery systems such as lipid or polymer based nanoparticles are designed to improve the pharmacological and therapeutic properties. Further, the metal based nanoparticles are also designed and developed to deliver the drugs and genes. The drug delivery system or gene delivery system consists of nanoparticles, nanoemulsions, liposomes and micelles. The polymeric and lipid based nano systems improved drug bioavailability and protect the encapsulated drug or gene from enzymatic attack.
The nanoparticles have been successfully applied as a drug delivery system and as a gene delivery system. The commonly used metals for nano-drug delivery system and gene delivery system include but not limited to gold, silver, platinum etc. The nanoparticles have been successfully applied as a delivery system for plasmid DNA in gene therapy. The nanoparticles provide an opportunity for targeting the DNA of interest into specific tissues or cells by attaching specific ligands on the surface of the nanoparticles.
The metal based nanoparticles for the drug delivery system show toxicity. The recent studies in this arena have shown that positively charged gold nanoparticles are found to enter kidney, while negatively charged gold nanoparticles remained in the liver and spleen. The positive surface charges of the nanoparticles decreases the rate of opsonization of nanoparticles in the liver, thereby affecting the excretory pathway. Even a relatively small size of the nanoparticles such as 5 nm can become compartmentalized in the perinephral tissues, and accumulate in the body over tissues. The advancement of research proves that targeting and distribution can be augmented by nanoparticles and the dangers of nano-toxicity have become an important question for the medical use in drug delivery.
Apart from the metal nanoparticles for gene delivery, there are two main systems for gene delivery. The two systems are viral vectors and non viral vectors.
Viral vectors are commonly used tool by molecular biologists to deliver genetic material into cells. The process can be performed inside a living organism (in vivo) or cell culture (in vitro). The viruses have evolved specialized molecular mechanisms to efficiently transport their genomes inside the cells they infect. The delivery of genes by viruses is termed as transduction. The viral vectors show high transfection efficiency, but there are some limitations of viral vectors such as non specificity, immunogenicity to the target cells and oncogenic effects. Also the viral vectors to deliver genetic material to cells come with logistical problems. There are limited member of viral vectors available can cause the body to develop an immune response, if the vector is seen as a foreign invader by the immune system. The viral vectors can infect healthy cells. It has been observed that the viral vectors get mutated and become virulent in nature.
The non viral vectors for gene therapy are preferred over viral vectors. The two main types of non viral gene delivery vectors are cationic liposomes and cationic polymers. The cationic polymers have been used to deliver DNA both in vitro and in vivo in terms of biocompatibility and low cytotoxicity. Specifically the cationic liposomes have potential to act as a delivery vector. However, their applications are limited to local delivery due to low stability and rapid degradation in the body. The cationic polymers include but not limited to chitosan, collagen, gelatin etc.
Chitosan is a natural cationic polymer obtained by deacetylation of its parent polymer chitin. Chitin is a polysaccharide widely distributed in nature. Chitosan has good biocompatibility, biodegradability, atoxicity and is non-allergic in nature. Chitosan is polycationic polymer and a weak base with a pKa value of 6.5. The physiochemical, structural, thermal, mechanical, biological and rheological properties of this polymer vary significantly with its molecular weight and degree of acetylation. Chitosan has been widely employed in gene delivery. Chitosan delivers drug or gene into the target cell by interacting with the cell membrane. The interaction of protonated amine group in chitosan with cell membrane results in a reversible structural reorganization of protein associated with tight junctions. The interaction leads to opening of tight junctions and thereby facilitating drug or gene delivery. Chitosan as a gene vector has disadvantages like relative inefficiency and low specificity. Also chitosan exhibit problems such as low solubility and low transfection efficiency.
Collagen is an abundant structural protein in all animals. In humans collagen comprises one third of the total protein. Collagen accounts for three quarters of the dry weight of skin and it is the main component of the extracellular matrix (ECM). Collagen is an important biomaterial in medical applications due to its special characteristics such as biodegradability and weak antigenicity. Thus collagen is a new type of biomaterial, which has been used in drug delivery systems and tissue engineering. A sequence motif of Arginine-Glycine-Aspargine (RGD) acts as cell-adhesion recognition motif. This sequence motif is found in collagen, fibronectin and tenascin C. The RGD sequence is the ligand for integrin-mediated cell adhesion, which involves a cascade of four overlapped reactions i.e. cell attachment, cell spreading, focal adhesion and cell cycle. The RGD sequence is the most effective cell recognition motif and has been used to stimulate cell adhesion on artificial surfaces. The soluble RGD peptide can inhibit the cell adhesion because it is the antagonist as well as the recognition sequence for integrin. The defining feature of collagen is an elegant structural motif in which three parallel polypeptide strands in a left handed, polyproline type-II (PPII) helical conformation coil about each other with a one-residue stagger to form a right handed triple helix. The tight packing of PPII helices within the triple helix mandates that every third residue is glycine (Gly). This results in a repeating sequence of XaaYaaGly. Xaa and Yaa can be any amino acid. This repeat occurs in all types of collagen, although it is disrupted at certain locations within the triple-helical domain of non-fibrillar collagens. There is a clear bias for Glutamine, Leucine and Phenylalanine in X position whereas Arginine and Lysine are seen to be preferred in the Y position of the Gly-X-Y triplets in all the five collagen chains. Interestingly Glycine and Threonine also show a preference for Y position in Type I and Type II collagens wile Methionine shows a similar preference in Type I, II and IV collagens. The residues showing preference for Y position can help stabilize triple helices as well as assemblies of triple helices through additional interactions.
Liposomes or phospholipid vesicles are self assembled colloidal particles that occur naturally and can be prepared artificially. Liposomes were introduced as drug delivery vehicles in 1970. The liposomes are mainly used for antifungal and anticancer drug delivery agents. The liposomes or phospholipids are polar lipids, whereas triglycerides are neutral lipids. The phospholipids are amphipathic molecules due to the presence of both polar head and non-polar tail. The phospholipids have the glycerol backbone structure as the neutral glycerides, but differ in the ester linkages resulted from a phosphoryl ester. In other words the phospholipids are composed of glycerol, 2 fatty acids and a phosphoryl ester group bonded to the third alcohol carbon of the glycerol backbone. The phospholipids are the primary building bocks of all cellular membranes. The vital organs such as the liver, reproductive tract and muscles contain high concentration of phospholipids. The membrane functions include cellular transport of nutrients and wastes, internal cellular pressure regulation and ion exchange.
Chitosan and glycerol phosphate (GP) system have shown potential for drug delivery and cell encapsulation. Gelation form of chitosan in glycerol phosphate is obtained when GP is added to chitosan solution. The pH of the solution increases as a result of the neutralizing phosphate groups. The chitosan-GP solutions can maintain their liquid state at physiological pH. The forces involved in the gelation process are hydrogen bonding, hydrophobic and electrostatic interactions. Chitosan is used for the production of nanoparticles by ionotropic gelation with tripolyphosphate.
The design of nanoparticle used for carrier of drugs and genes for treatment of diseases are desired to be delivered to a target cell and could be overcome of pharmaceutical and biopharmaceutical barriers and attached to target cell. The cationic liposomes have potential as a gene delivery vector; however their applications are limited to local delivery due to low stability and rapid degradation in the body. The chitosan is a cationic polymer has been used to deliver DNA both in vitro and in vivo with low cytotoxicity but still has some problem such as relative inefficiency and low specificity.
The combination of chitosan, collagen and phospholipids approve affinity to gene or drug, targeting and controlled release and protection from destroying of gene or drug until effect.
Hence there is a need to develop a nanoparticle based drug delivery system and gene delivery system without any threat of cytotoxicity. Also there is a need for a nanoparticle drug delivery system and gene delivery system for site directed gene delivery to release the drug slowly in a controlled manner to an action site. Further there is a need to develop a method for synthesizing the organic biomolecule based nanoparticle drug delivery system and gene delivery system.
The above mentioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification.